Capnocytophaga ochracea
1. Classification
a. Higher order taxa
Bacteria; Bacteriodetes; Flavobacteriia; Flavobacteriales; Flavobacteriaceae; Capnocytophaga
b. Species
NCBI: Taxonomy
Capnocytophaga ochracea
2. Description and significance
Capnocytophaga ochracea is a gram-negative fusiform-to-rod shaped bacterium that grows in clumps and moves by gliding despite having no flagella (1). This capnophilic aerotolerant anaerobe is found in the oral cavity of humans and contributes to early plaque formation on teeth by being a physical intermediate link between several Streptococcus species and F. nucleatum (2). Dental plaque is associated with periodontal disease and dental caries which is the single most prevalent disease in children (3).
In addition to oral disease, C. ochracea is known to cause sepsis in immunocompromised patients. In immunocompetent patients, intrauterine infections, endocarditis and septic arthritis may occur (4).
3. Genome structure
The genome of C. ochracea strain VPI 2845 consists of 2,612,925 base pairs all within one circular chromosome (5). It has a GC content of 39.59% which equates to 1,034,404 base pairs. The vast majority of the DNA is found in coding regions, 87.76% (5). There are a total of 2,252 genes of which 2,193 (97.38%) are protein-coding genes, 59 (2.62%) are RNA genes. There are a total of 4 rRNA operons (5). 471 (20.91%) of the genes have transmembrane helices which correlate with C. ochracea’s ecological role in the human oral cavity of plaque formation by binding to several bacteria (5).
4. Cell structure
C. ochracea are fusiform rods that form confluent colonies with a halo zone, the outer edge of a colony formed because of gliding (1). C. ochracea does not have flagella but it is still motile via a process called gliding in which the cell moves about its longitudinal axis. As cells glide out from the denser center of the colony, the thickness of cells decreases leading to a halo zone (1). Cells growing in a colony structure grow in an end-to-end fashion. Microcolonies ranging between 50-100 cells have been noticed throughout the entirety of the halo zone which is uncommon for gliding prokaryotes (1).
On the cell surface of C. ochracea, there are adhesin sites that allow for coaggregation between C. ochracea and F. nucleatum, Streptococcus and Actinomyces species (6). Simple sugars, such as L-rhamnose, β-methy-D-galactoside, lactose, and α-methy-D-galactoside, are effective inhibitors of C. ochracea-S. sanguis coaggregation. However, L-rhamnose is the most effective inhibitor of C. ochracea from binding with S. sanguis, A. naeslundii, or A. israelii (6).
5. Metabolic processes
Capnocytophaga ochracea is an aerotolerant anaerobe that requires either an anaerobic environment or 5% CO2 concentration of the gaseous form or 20 mM HCO3- in the hydrated form (7). All strains of C. ochracea are able to ferment glucose, sucrose, maltose and mannose, but most strains ferment amygdalin, fructose, galactose, lactose and raffinose to get an end product of acetate and succinate (5).
C. ochracea transports glucose across the cell membrane by a phosphoenolpyruvate:phosphotransferase system where glucose is converted into two molecules of phosphoenolpyruvate (PEP) by the Embden-Meyer-hof-Parnas pathway (8). Through this pathway, two NADH2 are produced and there is no net gain of ATP. One molecule of PEP goes back to the PEP phosphotransferase system to transport one molecule of glucose across the cell membrane (8). The other molecule of PEP continues to be catabolized via two pathways. One pathway converts PEP into an intermediate, oxaloacetate, by PEP kinase which fixes CO2 to PEP (8). Oxaloacetate is further catabolized into succinate producing ATP and NAD+ in the process. The second pathway converts PEP into pyruvate which generates one ATP. Pyruvate is then broken down into acetate producing another molecule of ATP (8).
The presence of yeast extract can alter the products and intermediates that accumulate in the cytoplasm. In a culture grown without yeast extract, the accumulation of acetate, pyruvate, oxaloacetate, and succinate is observed (8). However, in cultures grown with yeast extract, no pyruvate accumulates resulting in an increase in acetate formation. There also is a two-thirds decrease in oxaloacetate accumulation resulting in an increase of succinate formation (8).
6. Ecology
Habitat; symbiosis; contributions to the environment.
7. Pathology
How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.
7. Key microorganisms
Include this section if your Wiki page focuses on a microbial process, rather than a specific taxon/group of organisms
8. Current Research
Include information about how this microbe (or related microbes) are currently being studied and for what purpose
9. References
It is required that you add at least five primary research articles (in same format as the sample reference below) that corresponds to the info that you added to this page. [Sample reference] Faller, A., and Schleifer, K. "Modified Oxidase and Benzidine Tests for Separation of Staphylococci from Micrococci". Journal of Clinical Microbiology. 1981. Volume 13. p. 1031-1035.
